Dibutyl Phthalate

84-74-2

Hazard Summary-Created in April 1992; Revised in January 2000

Dibutyl phthalate is used in making flexible plastics that are found in
a variety of consumer products. It appears to have relatively low
acute (short-term) and chronic (long-term) toxicity. No information
is available regarding the effects in humans from inhalation or oral exposure
to dibutyl phthalate, and only minimal effects have been noted in animals
exposed by inhalation. No studies are available on the reproductive,
developmental, or carcinogenic effects of dibutyl phthalate in humans.
Animal studies have reported developmental and reproductive effects from
oral exposure. EPA has classified dibutyl phthalate as a Group D,
not classifiable as to human carcinogenicity.

Uses

Dibutyl phthalate is used to help make plastics soft and flexible.
It is used in shower curtains, raincoats, food wraps, bowls, car interiors,
vinyl fabrics, floor tiles, and other products. (1)

Sources and Potential Exposure

The largest source of exposure to dibutyl phthalate is from food,
possibly fish and seafood; levels in fish ranged from 78 to 200 parts
per billion (ppb). (1)

Dibutyl phthalate levels of 3.3 to 5.7 nanograms per cubic meter
(ng/m3) were detected in the air near New York City.
Dibutyl phthalate levels in rooms recently covered with polyvinyl chloride
tiles ranged from 15,000 to 26,000 ng/m3. (1)

Dibutyl phthalate was detected in some drinking water supplies at
levels ranging from 0.1 to 5 ppb. (1)

Assessing Personal Exposure

Tests are available that can detect dibutyl phthalate in blood and
body tissues, and the major breakdown products of dibutyl phthalate
can be measured in urine. (1)

Health Hazard Information

Acute Effects:

No information is available regarding the acute effects in humans
from inhalation or oral exposure to dibutyl phthalate. (1)

No information is available regarding acute effects in animals from
inhalation exposure to dibutyl phthalate, and oral animal studies have
reported minimal effects on the liver and a slight decrease in kidney
weight. (1)

Tests involving acute exposure of rats and mice have shown dibutyl
phthalate to have moderate toxicity
from inhalation exposure and low toxicity
from oral exposure. (2)

Chronic Effects(Noncancer):

No information is available regarding the chronic effects of dibutyl
phthalate from inhalation or oral exposure in humans. (1)

Limited information is available on the chronic effects of dibutyl
phthalate in animals from inhalation exposure; one study reported decreased
body weight gain and increased lung weight relative to body weight,
and another study reported an increase in brain weight as a percent
of body weight. (1)

Chronic oral studies in animals have reported effects on the liver.
(1)

EPA has not established a Reference Concentration (RfC)
for dibutyl phthalate. (3)

The Reference Dose (RfD)
for dibutyl phthalate is 0.1 milligrams per kilogram body weight per
day (mg/kg/d) based on increased mortality in rats. The RfD
is an estimate (with uncertainty spanning perhaps an order of magnitude)
of a daily oral exposure to the human population (including sensitive
subgroups) that is likely to be without appreciable risk of deleterious
noncancer effects during a lifetime. It is not a direct estimator
of risk but rather a reference point to gauge the potential effects.
At exposures increasingly greater than the RfD,
the potential for adverse health effects increases. Lifetime exposure
above the RfD does not imply
that an adverse health effect would necessarily occur. (3)

EPA has low confidence in the study on which the RfD
was based because the study used few animals of one sex only and it
was not indicated whether the 50 percent mortality observed early in
the study was considered treatment-related, nor was the cause of death
indicated; low confidence in the database because the study is the only
subchronic bioassay of dibutyl phthalate reported in the literature;
and, consequently, low confidence in the RfD.
(3)

Reproductive/Developmental Effects:

No studies are available regarding the reproductive or developmental
effects of dibutyl phthalate in humans from inhalation or oral exposure.
(1)

Animal studies have reported developmental effects, such as reduced
fetal weight, decreased number of viable litters, and birth defects
(neural tube defects) in mice exposed orally to dibutyl phthalate.
Reproductive effects, such as decreased spermatogenesis and testes weight,
have also been reported in oral animal studies. (1,5,6)

Cancer Risk:

No information is available on the carcinogenic effects of dibutyl
phthalate in humans or animals. (1)

EPA has classified dibutyl phthalate as a Group D, not classifiable
as to human carcinogenicity. (3)

Physical Properties

Dibutyl phthalate is an odorless and colorless to faint yellow oily
liquid. (1)

The chemical formula for dibutyl phthalate is C16H22O4,
and the molecular weight is 278.35 g/mol. (1)

The vapor pressure for dibutyl phthalate is 1.0 × 10-5
mm of Hg at 25 °C, and it has a log octanol/water partition coefficient
(log Kow) of 5.60. (1)

Health Data from Inhalation Exposure

ACGIH TLV--American Conference of Governmental and Industrial
Hygienists' threshold limit value expressed as a time-weighted average;
the concentration of a substance to which most workers can be exposed
without adverse effects. LC50 (Lethal Concentration50)--A calculated
concentration of a chemical in air to which exposure for a specific length
of time is expected to cause death in 50% of a defined experimental animal
population. NIOSH IDLH -- National Institute of Occupational Safety and Health's
immediately dangerous to life or health concentration; NIOSH recommended
exposure limit to ensure that a worker can escape from an exposure condition
that is likely to cause death or immediate or delayed permanent adverse
health effects or prevent escape from the environment. NIOSH REL--NIOSH's recommended exposure limit; NIOSH-recommended
exposure limit for an 8- or 10-h time-weighted-average exposure and/or
ceiling. OSHA PEL--Occupational Safety and Health Administration's permissible
exposure limit expressed as a time-weighted average; the concentration
of a substance to which most workers can be exposed without adverse effect
averaged over a normal 8-h workday or a 40-h workweek.

The health and regulatory values cited in this factsheet were obtained
in December 1999.aHealth numbers are toxicological numbers
from animal testing or risk assessment values developed by EPA. bRegulatory numbers are values that have been
incorporated in Government regulations, while advisory numbers are nonregulatory
values provided by the Government or other groups as advice. OSHA
numbers are regulatory, whereas NIOSH and ACGIH numbers are advisory.

National Institute for Occupational Safety and
Health (NIOSH). Pocket
Guide to Chemical Hazards. U.S. Department of Health and Human
Services, Public Health Service, Centers for Disease Control and Prevention.
Cincinnati, OH. 1997.